Casting metals



Patented May 11, 1926.

UNITED STATES PATENT" OFFICE.

ADOLF BECK, or eRIEsnEIM-ou-THn-MAIN, GERMANY, ASSIGNOR '10 cHEmIsoHE FABRIK GRIESHEIM-ELEKTRON, or GRIESHEIM-ON-THE-MAIN, GERMANY;

CASTING METALS.

No Drawing.

'to get oxidized in heated condition, the casting being'efi'ected with the aid of the sand moulds hitherto generally employed, such moulds must be carefully dried, in ,order to obtain good castings. It the moulds are not dried carefully, a reaction will take place between the metal and the water present in the mould and more especially 111 the sand,

and a similar reaction is then liable to take] placebctwccn the metal and the moulding material, such as sand, such reaction rendering'the casting at least interior in outer appearance. If great quantities of water are still present in the mould, explosion-like phenomena are even likely to occur.

In an application for patentot' the United. States Scr. No. 563,717, tiled on May 25, 1922 by Karl Gersloach, ()sk'ar Ilermann \Veber and myseli a method ot'masting is described which allows avoiding the ignition of the metal, provided that the moulds are carefully dried, this method substantially consisting in providing the mould with a coating of a material which will not react with the molten metal, either as such or in the form of its products of oxidation. I assume this protective effect to be due-to the action of the gases or vapors developed from the protective material in contact with 40 the hot metal and which prevent the access of air on steam to the metaL I have now ascertained that by employing certain mate-rials in the preparation of the mould for casting, I obtain the surprising result that they drying of the mould and of the sand'contained therein is no more necessary, the presence of water being innoxious so that I am now enabled to cast the metals in question in comparatlvely wet.

moulds. These materials (which may be called protective substances) are those described in the specification above cited, as being adapted to prevent oxidation of the castings when intensely dried moulding sand is used, and more especiallysulphur and Application filed m 16, .1923. Serial No. 651,959.

found that bicarbonate-s, urea, boric acid, as

well as i'nixtures of these substances have proved suitable. The peculiar action of the protective substance has not yet been cleared up completely; It seems that the steam and air are sufficiently diluted with gases ;or vapors produced from these substances or that the prevent in some other Way the access 0t water vapor to the hot metal so that no visible action. of the steam'upon the metal occurs. However, I wish it to be understood that. this is merely an attempt to expain the peculiar action of the protective substances.

I may apply the protective materials in the form of a watery paste, suspension or emulsion on the surface of the mould after it has set, or I may admix a suitable quantity of such materials to the sand before making the mould. If sulphur is employed as protective material and sand as moulding material, an addition of" 16% sulphur to the sand has proved advantageous. I prefer admixing the protective material to the said or the like for the reason that the powdering orspraying on will sometimes be ditticult in such places of the mould which are not easily acccssible. Moreover, by admixing the protective material to the sand a sound protective effect is obtained even atthose places where the casting is comparatively thick such as gates, inasmuch as the protective gases or vapors are not developedmcrely on the surface of the mould, as in the case of superficial powdering orspraying on, but also from deeper layers in correspondence with the gradual heating of the mould by the metal a ficient.

A similar effect within the's dope of my invention might be obtained also by developing gases or vapors from the rotective materials spoken of above out-side the mould and introducing them into the mould immediately before the casting. However, if this.

is done, .the protective 'efl'ect will be less powerful for the reason that the concentrametal, as if they are generated inthe moulditself.

I wish it to be understod thatI do not desire to be limited to the particular substances and modes of proceeding described, for obvious modifications will occur to a person skilled in the art.

I claim:

1. The method of preventing easily oxidizable metals and alloys for oxidizing on being cast in undried moulds, comprising mixing moulding material with a non-metallic substance incapable of reaction with said metal and adapted, when heated by the heat emitted from the cast metal, to form on the surface of the casting a layer preventing the casting beingspoilt by the access of air and water vapor.

. 2. The method of preventing easily oxidizable metals and alloys for oxidizing on being cast in undried moulds, comprising mixing moulding material with a non-metallic substance incapable of reaction with said metal and adapted, when heated by the heat emitted from the cast metal, to form on the surface of the-casting a layer preventing the casting being spoilt by the access of air and water vapor, forming said mixture into a mould and covering the surface of said mould with said substance.

3. The method of preventing easily oxidizable metals and alloys for oxidizing on being cast in undried moulds, comprising mixing with the moulding material boric acid. 7

4. The method of preventing easily oxidizable metals and alloys for oxidizing on being cast in undried moulds, comprising mixing with themoulding material a quantitiy of borie acid substantially not exceeding 1 per cent of such material.

In testimony whereof I atfix my signature.

ADOLF BECK. 

